The invention is directed to a process for the production of aqueous solutions of sodium salts of .alpha.-aminocarboxylic acids practically free from foreign salts by alkaline saponification of the corresponding hydantoin at a temperature between 110.degree. and 180.degree. C.
It has been known for over 70 years to produce the various .alpha.-aminocarboxylic acids by alkaline saponification of the corresponding hydantoins at a temperature between 110.degree. and 180.degree. C. As saponification agent there generally is employed sodium hydroxide and/or sodium carbonate. In the saponification there is then formed an aqueous solution which besides the sodium salt of the .alpha.-aminocarboxylic acid necessarily also contains a more or less large amount of one half to one mole per mole of .alpha.-aminocarboxylic acid. The isolation of the .alpha.-aminocarboxylic acid from this solution then frequently is carried out by adsorption on an acid ion exchanger and subsequent elution with a suitable eluting agent.
However, in this type of working up the content of sodium carbonate in the solution is disturbing because it reduces considerably the capacity of the ion exchange plant. Therefore it is desirable to carry out the saponification of the hydantoin in such a manner that the saponification mixture besides the .alpha.-aminocarboxylic acid salt contains as low as possible amounts of dissolved foreign salts.